Crude oil produced from underground reservoirs often contains many entrained compounds. For example, an oil well will frequently produce large quantities of water, gas, carbon dioxide, solids and crude oil. To facilitate the pumping of the oil from an underground reservoir, devices such as gas anchors are commonly used to prevent large quantities of gas from being produced with the oil. If gas is produced with the oil, gas locks can prevent the efficient operation of the pumping mechanism. In addition, gas anchors and other devices can be used to prevent solids in the production fluids from being drawn into the pumping mechanism.
In the production of oil from an underground reservoir, paraffin compounds associated with the hydrocarbons may precipitate onto, solidify and coat the surfaces of the pumping pipes and equipment. The solidification of paraffins may be due to a lower temperature which causes the crystallization of the paraffin, or may be due to the reaction of paraffin compounds with water and other fluids produced from the reservoir. In any event, the accumulation of paraffin solids on production pipes and equipment impairs the operation of the equipment by reducing pumping efficiency and increasing production costs.
Different techniques have been developed to remove the accumulation of paraffin solids from pumping pipes and equipment. For example, U.S. Pat. No. 4,011,906 to Alexander et al discloses a device which uses hot water to remove paraffin deposits from production tubing. In U.S. Pat. No. 4,138,931 to Hermann et al, a hydraulic pump inhibits the formation of deposits by using plungers to create a fluid flow which produces a scrubbing effect on the cavity surface. In U.S. Pat. No. 194,704 to Means, water is removed from the well bore to prevent paraffin from forming in the well.
These techniques do not prevent the accumulation of paraffin deposits but are designed to remove the paraffin after it has accumulated. Accordingly, a need exists for a process and apparatus which can prevent the accumulation of paraffin deposits in pumping pipes and equipment.
In addition to the well-known problem of paraffin contamination of oil wells, the accumulation of scale on the surfaces of, as well as the corrosion of the pipes, flow tubes, pumps and other equipment is a problem with both oil and water wells. The build-up of contaminants constricts the flow the pumped fluid, decreasing the well's efficiency, and corrodes the equipment, necessitating replacement. The problem is particularly acute where the distance the fluid must be pumped is long or where the mineral content of the fluids flowing in the well system is high and the deposition of compounds of these minerals is production and economic difficulties. In addition to paraffin, particularly bothersome are compounds such as calcium carbonate/sulfate. iron oxide/sulfide, as well as hydrogen sulfide, free sulfur, and sodium salts.
Contaminant deposition is also a problem for equipment that utilizes water for cooling, heating or other treatment, such as steam or hydronic boilers, chillers, cooling towers, and humidifiers. Contaminants also present maintenance problems for cold weather cooling equipment that utilizes ethylene glycol. Scale buildup in these systems requires periodic shutdown for chemical or mechanical de-scaling and flushing.
One solution to this problem is to chemically treat the fluid; this is expensive and introduces another contaminant that must be removed, causing delays and increased costs. Another solution is to prevent deposition of precipitates of these mineral compounds. If the contaminants can be maintained in colloidal form or in suspension and prevented from depositing on the equipment walls, they will not accumulate on or corrode the tubing walls and equipment surfaces, thus eliminating the problems caused by these contaminants.
Many devices have been proposed to overcome this contaminant problem. Many of these are an inserts having specific metallurgies (predominantly copper in most) that are placed within a pipe to provide constricted or tortuous flow paths for the liquid. Such arrangements are shown in U.S. Pat. Nos. 3,448,034 to Craft; 3,919,068 to Gary; 4,933,089 to Newton; and U.S. Pat. No. 5,204,006 to Santoli. These inserts allegedly have a polarizing effect on the fluid in the tube to eliminate any affinity between the mineral compounds and the surfaces of the flow system and prevent precipitation of the compounds and prevent their deposition on the equipment walls.
U.S. Pat. No. 3,891,394 to Smith et al provides an insert which allegedly produces so-called "seed" crystals that attract deposited scale and remain in suspension in the fluid due to the turbulence created by the insert. U.S. Pat. No. 1,608,709 to Mills proposes a slightly different arrangement by providing a sacrificial insert of zinc in the fluid flow which is insulated from the fluid pipe and which corrodes in place of the pipe.
None of these inserts have become an industry standard, and thus appear to only be minimally effective in preventing scale formation and corrosion.
Another solution that has been tried in oil wells is the use of permanent magnets placed outside the pipe to induce a magnetic field within the pipe through which the oil flows. This has been found to have limited effectiveness on current oil wells.
All of the previous devices have been developed for current relatively shallow (6000 ft.) wells. There is currently a proposal to begin deep (6000 ft.) oil well drilling. This extreme length of oil travel and the depths encountered will present new problems of preventing contaminant deposition and corrosion.
It would be desirable to provide a device which provides improved contaminant neutralization in all types of confined fluid systems utilizing water, oil or glycol, such as well production, cooling, heating and humidification.
It would also be desirable to provide a device which more effectively neutralizes contaminants in a liquid to prevent their deposition on the walls of the liquid container.
It would further be desirable to provide a device which is placed in the line of flow of a deep oil well which prevents deposition of paraffin and other contaminants onto the walls of the pipeline transporting the liquid.